Context: Microvascular processes have been hypothesized to play a greater role in the development of coronary heart disease (CHD) in women than in men; however, prospective clinical data are limited. Objective: To examine the association between retinal arteriolar narrowing, a marker of microvascular damage from hypertension and inflammation, and incident CHD in healthy middle-aged women and men. Design, Setting, and Participants: The Atherosclerosis Risk in Communities Study, an ongoing prospective, population-based cohort study in 4 US communities initiated in 1987-1989. Retinal photographs were taken in 9648 women and men aged 51 to 72 years without CHD at the third examination (1993-1995). To quantify retinal arteriolar narrowing, the photographs were digitized, individual arteriolar and venular diameters were measured, and a summary arteriole-to-venule ratio (AVR) was calculated. Main Outcome Measure: Risk of CHD associated with retinal arteriolar narrowing. Results: During an average 3.5 years of follow-up, 84 women and 187 men experienced incident CHD events. In women, after controlling for mean arterial blood pressure averaged over the previous 6 years, diabetes, cigarette smoking, plasma lipid levels, and other risk factors, each SD decrease in the AVR was associated with an increased risk of any incident CHD (relative risk [RR], 1.37; 95% confidence interval [Cl], 1.08-1.72) and of acute myocardial infarction (RR, 1.50; 95% Cl, 1.10-2.04). In contrast, AVR was unrelated to any incident CHD in men (RR, 1.00; 95% Cl, 0.84-1.18) or to acute myocardial infarction (RR, 1.08; 95% Cl, 0.85-1.38). Conclusion: Retinal arteriolar narrowing is related to risk of CHD in women but not in men, supporting a more prominent microvascular role in the development of CHD in women than in men. Future work is needed to confirm these findings
